Severe back pain, limited motion, and nerve damage may be caused by injured, degraded, or diseased spinal anatomy. Affected spinal joints, and particularly discs and ligaments, can be difficult to treat externally and may necessitate surgery.
In some surgical treatments, posterior rods may be attached to variously affected spinal levels to inhibit or limit motion. Some posterior rods are rigid rods which substantially, if not totally, eliminate freedom of motion for bending in flexion and extension. Other important motions may similarly be eliminated.
During implantation, treating physicians frequently use rigid bone screws or anchors to attach the rods to some vertebrae, and because perfectly aligning the rods and screws can be difficult, use non-locking screws to attach the rods to other vertebrae. Accordingly, the treating physician must decide in advance or during the procedure which type of screw to use in each location.
The present disclosure is directed to a system that overcomes one or more of the shortcomings of the prior art by providing dynamic stabilization to vertebrae of a spinal column.